Containers or bags formed of heavy weight, multiple ply paper are conventionally employed for containing, storing and shipping flowable, fine powdery materials and small sized granular products, such as starch, human and animal food products, chemicals, cement and the like. A continuing problem has been providing reclosing and/or resealing means for use when a portion of the contents of the container remains after partial removal.
Various procedures and products have been suggested in the prior art for overcoming the problems of reclosing containers. A variety of recloseable and resealable containers for such uses are available in the art. Packagers and suppliers of adhesive products to packagers, have sought in various ways to provide resealable closures for such packages which are reliable, and easy and convenient to use.
U.S. Pat. No. 3,154,239 (Madsen) discloses a resealable bag in which the sealing device is a paper flap foldable over an open end of the bag. One side of the flap is secured to the bag with a permanent adhesive, while the other side of the flap is releasably attached to the bag by a pressure sensitive adhesive.
U.S. Pat. No. 4,441,613 (Hain et al), discloses a resealable bag for containing a flowable product which includes a plurality of panels hingedly coupled along fold lines, an opening at one end of the bag, a flap hingedly coupled to one panel along a fold line for overlapping an opposite panel and closing the opening, and a strip of adhesive tape for opening and resealing the flap. An adhesive layer extends across the entire width of the flap to seal the flap to the opposite panel. The adhesive layer seal can have a reduced bonding strength adjacent one end of the flap to facilitate opening of the flap at the reduced bond strength section. The reduced bonding strength is provided by an abhesive coating comprising kaolin clay.
U.S. Pat. No. 4,543,139 (Freedman et al), for example, addresses the problem of loss of adhesion through repeated use or due to contamination by employing adjoining strata of pressure-sensitive adhesive. The two adhesive strata have different adhesion to the substrate. The adhesive strata are used as a recloseable fastener and are intermixed in the course of reclosing and reopening the package. The reopening action compensates for contamination of the adhesive occurring at the reseal interface.
U.S. Pat. No. 4,911,563 (Ciani) discloses a re-closeable package having a bifurcated adhesive member secured to the body portion of the package at a distance from the opening thereof. The member has a jaw-like construction with a hinge line about which one of the jaws pivots. In use, the jaws are opened by the user, the re-closed, folded end of the package is inserted into the jaws, and the jaws subsequently closed to retain the package in re-closed condition.
U.S. Pat. No. 5,035,518 (McClintock) describes a hinge type pressure sensitive resealable closure system for a container, including a separate flat strip of material permanently adhered at one surface to the container. Another surface of the strip includes a removable pressure sensitive adhesive, to be removably attached to the container.
U.S. Pat. Nos. 5,824,380 and 5,855,434 (Hagen) both disclose a package reclosure label strip which is secured by a pressure-sensitive adhesive to the package. In U.S. Pat. No. 5,824,380, a Z-folded top sheet has a first panel permanently adhered to the upper surface of the base sheet, a second panel folded back over the first panel with an edge extending past the first panel that is releasably adhered to the base sheet, and a third panel folded back over the second panel and extending beyond the second panel to an opening tab which is resealably adhered to the package. The label can be opened or extended by lifting the opening tab off the package and breaking the releasable bond between the second panel and the base sheet. In U.S. Pat. No. 5,855,434, the top sheet is not Z-folded, but operates substantially similarly to the strip disclosed in U.S. Pat. No. 5,824,380.
U.S. Pat. No. 6,048,100 (Thrall et al) discloses a resealable closure for a bag. The upper ends of bag wall members are folded downwardly adjacent the front wall member to form a flap which extends across the upper end of the bag with the upper flap being permanently sealed by an adhesive to the front wall member except for a flap portion adjacent one of the side wall members. The resealable closure is positioned between the flap portion and the front wall of the bag and permits the flap portion to be opened to form a pour opening in the upper corner of the bag. The flap portion may be resealed by the resealable closure. The containers described in U.S. Pat. No. 6,048,100 include a strong adhesive which results in difficult and noisy re-opening.
The foregoing containers and materials have achieved a certain level of acceptance. However, difficulties still exist. The adhesives become contaminated by the container contents. Adhesion strength is lost upon repeated use. Obtrusive devices are attached to the outside of the container. Difficult-to-use closure means are employed, such as reclosure strips, which must be either freed or reattached for use after opening the container. Another continuing problem is the noise associated with re-opening the adhesively closed reclosure device. The noise is often loud and annoying, and may have a sound like woven fabric being violently torn. Consumers and users of the containers remain unsatisfied because of aesthetically undesirable effects, such as noisy opening.
Despite improvements in resealable containers, a need remains for a resealable closure which is releasable, and which provides both a strong, secure closure, and easy re-opening without undue noise.